European patent application EP 1 129 702 discloses a composite structure having an adhesive matrix that is situated between two support layers that can be constituted by non-woven fabrics. Such a structure can be wetted before use, and then one of its surfaces can be applied to the skin, so as to release onto said skin at least one active ingredient contained in the matrix.
When the structure is asymmetrical, it can be necessary to indicate to the user which surface is the application surface.
To do this, one solution can consist in coloring one of the support layers.
However, the non-woven fabric sheets generally proposed by manufacturers are white, and the production of a colored non-woven fabric can turn out to be expensive when the quantities required are relatively small.